It probably depends upon just what species of pig you are talking about, but the feral pigs on the Channel Islands (USA)provide a ready source of food with nothing more than a knife. And I have fended off a "charging" pig with a well placed boot on the snout. If you need food, you are not going to go after the big tough boars, but something a little more vulnerable - like a piglet.
Actually, you don't even need a knife. One of the guys at the park dispatched a fairly mature pig with an elk antler.
One thing about islands - they have shorelines and intertidal areas. The food in the intertidal, at least on the islands I have seen, makes the food problem a piece of cake (well, actually abalone, urchin, or limpet). I can't think of a nicer place to survive than an island of the general type you describe. <img src="images/graemlins/laugh.gif" alt="" />